Abstract
Substantial reductions in U.S. cigarette smoking and associated chronic diseases over the past 50 years have benefited health. Unfortunately, those reductions have distributed unevenly throughout the population. Smoking remains prevalent and even increasing among certain vulnerable populations: economically disadvantaged groups, those with other substance-use disorders or mental illness, certain ethnic and racial minorities, and gender and sexual minorities. Moreover, other unhealthy behavior patterns (physical inactivity, unhealthy food choices, risky sexual behavior, poor adherence to medical preventive regimens) and associated chronic diseases are also overrepresented in many of these same populations. Disparities in unhealthy behavior patterns contribute to health disparities and escalating health care costs, underscoring the need for more effective behavior-change strategies. This report reviews research on the efficacy of financial incentives for reducing smoking in vulnerable populations, while also touching on applications of that behavior-change strategy for promoting other health-related behavior changes in vulnerable populations.
Keywords
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Financial incentives can reduce smoking and promote health in pregnant women and other vulnerable populations.
Key Points
Cigarette smoking and other unhealthy behavior patterns (lifestyle) are overrepresented in economically disadvantaged and other vulnerable populations.
These unhealthy behaviors increase risk of chronic disease and premature death, increase health care costs, and contribute to the growing problem of health disparities.
Considerable evidence indicates that financial incentives help meet the need for more effective strategies to promote smoking cessation and other health-related behavior changes in vulnerable populations.
Introduction
Prevalence of cigarette smoking in the United States and other developed countries has decreased substantially since the landmark publication of the 1964 U.S. Surgeon General’s report on smoking and health. Unfortunately, that progress has been unevenly distributed in the overall population, with economically disadvantaged individuals, those with other substance-use disorders or mental illness, certain ethnic/racial minorities, and gender and sexual minorities, exhibiting smaller decreases or in some cases (e.g., economically disadvantaged women) increases in smoking prevalence. Economically disadvantaged women are also of particular concern because they are at increased risk of smoking during pregnancy, with associated adverse health impacts on pregnancy outcomes and offspring health.
Unevenness in prevalence of cigarette smoking is a major contributor to the unsettling and growing problems of health disparities in the United States and other developed countries (Schroeder, 2016). However, cigarette smoking is not the only lifestyle contributor to health disparities. For example, prevalence of obesity (especially when accompanied by Type 2 diabetes), unplanned pregnancies, and non-adherence with medical prevention and treatment regimens are also overrepresented in many of these same vulnerable populations and contributors to health disparities. There is growing recognition of these challenges on individual and population health and the need for more effective behavior-change strategies within the U.S. National Institutes of Health, the Centers for Medicare and Medicaid Services, and other health care agencies in the United States and abroad. The overarching purpose of the present report is to review the emerging behavioral economic literature on the efficacy and effectiveness of financial-based incentives (vouchers, prizes, cash) for promoting health-related behavior change.
Scientific Rationales for Incentives
The scientific rationale for incentives to promote smoking-cessation and other health-related behavior change (S. T. Higgins, Silverman, Sigmon, & Naito, 2012; S. T. Higgins, Washio, et al., 2012) finds overwhelming evidence that nicotine is the constituent in cigarettes that drives chronic smoking, dependence, and associated adverse health outcomes through basic learning and conditioning processes. More specifically, nicotine stimulates dopamine-based mesolimbic brain reward centers, which in turn drives repeated use and dependence through the behavioral science process of reinforcement. Sugar, fat, salt, and sexual activity also stimulate these same reward centers and reinforcement processes in promoting overconsumption of unhealthy foods, risky sexual behavior, and so on. These basic learning and conditioning processes evolved to support successful foraging for food, water, sexual partners, and other activities critical to survival. Hence, their effects are often robust and resilient. Financial incentive programs act through these same processes (Knutson, Adams, Fong, & Hommer, 2001). That is, they leverage the same neurobiological reward centers and reinforcement and associated learning and conditioning processes that underpin the acquisition and maintenance of unhealthy behavior patterns to promote healthier choices.
Behavioral economics research has enhanced our understanding of the role of these conditioning processes—by identifying fundamental biases in how humans make choices that can increase risk of acquiring unhealthy behavior patterns and undermine efforts to change them. In particular, temporal discounting (Bickel, 2015) refers to a bias toward preferring immediate over delayed reinforcement, even when the amount of reward associated with the more immediate option is less valuable (Bickel & Marsch, 2001). Although humans all share this bias, considerable individual differences in the degree of temporal discounting implicate many factors, including younger chronological age, lower educational attainment, and more deprivation. Greater temporal discounting increases risk of cigarette smoking, unhealthy food choices and physical inactivity, risky sexual practices, and a growing list of other unhealthy behavior patterns (e.g., Barlow, Reeves, McKee, Galea, & Stuckler, 2016; Collado, Johnson, Loya, Johnson, & Yi, 2016; Jackson & MacKillop, 2016; MacKillop, 2016; McClelland et al., 2016). Financial incentive programs leverage this bias toward immediate outcomes by providing a salient, short-term positive consequence for choosing the healthier options.
Financial incentives also increase activity in brain regions associated with attention, error monitoring, and other executive functions important to successful goal seeking (Aston-Jones & Cohen, 2005; Mueller et al., 2009). These processes often diminish among chronic smokers and those with other substance-use disorders, as well as those residing in socioeconomically disadvantaged settings (Garavan & Hester, 2007; Lundqvist, 2005; Ursache, Noble, & Pediatric Imaging, Neurocognition and Genetics Study, 2016). That is, in addition to increasing motivation for making healthier choices, financial incentives also engage additional behavioral and neurobiological processes important to successful goal attainment.
Background: Support for Incentives in the Treatment of Substance-Use Disorders
Before detailing the evidence on financial incentives for smoking cessation and other health-related behavior change among vulnerable populations, consider the larger empirical support for this approach. An extensive scientific literature supports financial incentives to promote health-related behavior change (e.g., Supplemental Issue of Preventive Medicine on Incentives and Health, S. T. Higgins, Silverman, et al., 2012); among those with substance-use disorders, the treatment approach is also called contingency management (S. T. Higgins, Silverman, & Heil, 2008). Financial incentives in health promotion gained considerable recognition in the early 1990s as part of multi-element interventions for outpatient treatment of cocaine dependence. The intervention offered vouchers exchangeable for retail items, contingent on objective evidence of recent abstinence from cocaine use, in combination with intensive counseling. The intervention promoted abstinence from cocaine use in well-controlled randomized clinical trials with dependent outpatients in a context where almost every other treatment model failed miserably (e.g., S. T. Higgins et al., 1994). Soon thereafter, financial incentives’ efficacy was investigated across a range of abused drugs, populations, and geographic regions.
The literature on financial incentives targeting substance-use disorders has been reviewed in a three-report series that encompassed all controlled studies on treating substance-use disorders using vouchers and related monetary incentives from 1991 through 2014 (Davis et al., 2016; S. T. Higgins, Sigmon, & Heil, 2011; Lussier, Heil, Mongeon, Badger, & Higgins, 2006). Overall, a total of 177 controlled studies were reviewed in that series with 155 (88%) of them demonstrating efficacy. It is this larger literature that provided the evidence to support adoption of financial incentives as (a) part of intensive outpatient treatment for substance-use disorders within the U.S. Veterans Administration hospital system (Petry, DePhilippis, Rash, Drapkin, & McKay, 2014), (b) a component of employee wellness programs offered by the majority of major U.S. employers (Mattke et al., 2013), and (c) a cornerstone of the empirical rationale for the World Bank’s Conditional Cash Transfer program to combat chronic poverty in developing countries (Ranganathan & Lagarde, 2012). Where we believe the approach still has considerable unrealized potential is in public-sector efforts to promote health and reduce disparities in vulnerable populations in the United States and other developed countries.
A common criticism is incentives only provide benefit while they remain in place. Of course, even short-term behavior change can matter during pregnancy and in other contexts where healthy choices can have long-term implications (e.g., perioperative smoking cessation, decisions on using long-term reversible contraceptives). Nevertheless, treatment-outcome studies with cocaine-dependent outpatients showed benefits from incentives 1 to 2 years after they were discontinued (S. T. Higgins et al., 2007; Higgins, Wong, Badger, Ogden, & Dantona, 2000). Although relapse is a problem with all health-related behavior-change interventions, this is not unique to or greater with incentives. Indeed one third of studies that included post-treatment follow-up in the Davis et al. (2016) review noted significant treatment effects at one or more post-treatment assessments.
Financial Incentives for Smoking Cessation in Vulnerable Populations
A well-developed body of evidence supports the efficacy, effectiveness, and cost-effectiveness of incentives for promoting smoking cessation among pregnant women (Cahill, Hartmann-Boyce, & Perera, 2015; S. T. Higgins & Solomon, 2016). Promising but more preliminary results support the efficacy of incentives for promoting smoking cessation with adolescents, low-income adults, and individuals with co-morbid substance-use disorders or mental illness. Overall, we are aware of 31 controlled studies published in peer-reviewed journals that examined the efficacy of financial incentives in promoting smoking cessation in vulnerable populations between January 1995 through October 2016. Incentives produced a statistically significant treatment effect in 28 of those 31 (90%) reports, providing strong evidence for the potential to make a substantive contribution to decreasing smoking in these vulnerable populations.
Pregnant Women
Smoking during pregnancy can cause catastrophic pregnancy complications and adverse effects on fetal development, infant health, and later-in-life disease risk among smoke-exposed offspring (Bakker & Jaddoe, 2011; Cnattingius, 2004; Dietz, England, Shapiro-Mendoza, Farr, & Callaghan, 2010; Holz et al., 2014; Jiang, Ma, Wang, & Liu, 2013; Suter, Anders, & Aagaard, 2013). Smoking during pregnancy is largely a problem among economically disadvantaged women, due to greater prevalence, higher nicotine dependence, and greater difficulties in quitting smoking upon becoming pregnant, compared with more affluent women. The search for effective treatments entails more than 77 controlled trials involving 29,000 women since 1984 (Sexton & Hebel, 1984). Meta-analyses support the efficacy of various treatment models (Chamberlain et al., 2013; Lumley et al., 2009). However, the treatments produce only small treatment effects that on average increase cessation rates by approximately 6% above controls. The exception is financial incentives, which produced an average 24% increase.
To illustrate this approach, we detail controlled clinical trials at the University of Vermont developed this voucher-based incentives approach to behavior change. Participants are biochemically verified smokers recruited from ObGyn clinics in the greater Burlington, Vermont area. They are assigned to an incentives condition wherein they earn vouchers redeemable for retail items, contingent on biochemically verified abstinence from recent smoking, or a control condition wherein they receive vouchers of equal value to those delivered in the incentives condition but independent of smoking status. This keeps controls for providing extra material resources across the two conditions. Women in both conditions continue to receive the smoking cessation recommendations through their ObGyn providers. Vouchers start at US$6.25 for the first assessment indicating successful smoking abstinence and escalate in value for each consecutively confirmed negative test result to a maximum of US$45 where they are maintained through 12 weeks postpartum. A positive test result resets voucher values back to the initial low level, to reinforce sustained abstinence and discourage even brief relapses. However, to encourage women to keep trying to abstain following a relapse, voucher value is returned to the value it was at prior to the reset if a woman is able to provide two consecutive negative tests following the reset. At 12 weeks postpartum, all incentives discontinue. Women complete a final assessment at 24 weeks postpartum. Maximal incentive earnings if a woman abstains throughout the approximately 9-month intervention is ~US$1,180, but because not all women successfully quit, average earnings in both conditions are ~US$450 in each.
Abstinence averages significantly greater under contingent incentives than control conditions at late pregnancy (34% vs. 7%) through 12 weeks postpartum (24% vs. 3%), and remains significant at 24 weeks postpartum (14% vs. 1%), 12 weeks after incentives cease. Mean birth weight is ~200 g greater among infants born to mothers treated in the incentives condition, as is mean gestational age at delivery (by nearly a week). Women treated with incentives also breastfed longer (T. M. Higgins, Higgins, et al., 2010) and were less likely to experience postpartum depressive symptoms (Lopez, Skelly, & Higgins, 2015).
Overall, of seven controlled clinical trials, all but one (86%) noted significantly greater cessation during pregnancy among women treated with incentives compared with controls (Donatelle, Prows, Champeau, & Hudson, 2000; Heil et al., 2008; S. T. Higgins et al., 2004; S. T. Higgins et al., 2014; Ondersma et al., 2012; Tappin et al., 2015; Tuten, Fitzsimons, Chimsolm, Nuzzo, & Jones, 2012). In a third, most recent meta-analysis (Cahill et al., 2015; eight trials involving 1,297 women), those treated with incentives had 3.79 times greater odds of achieving late-pregnancy abstinence compared with controls, and 3.61 times greater odds at final assessment as far out as 24 weeks postpartum.
The effectiveness of this incentives intervention when delivered by clinicians in a clinical rather than research setting was demonstrated in a large urban community hospital in Chesterfield, England, where incentives produced cessation rates of 20% above control levels (Ierfino et al., 2015). That difference aligns well with the 24% increase in the meta-analyses of the efficacy trials.
Last, one trial compared the incremental cost per late-pregnancy quitter in the incentives versus control treatment (Boyd, Briggs, Bauld, Sinclair, & Tappin, 2016). Comparing against standardized incremental cost-effectiveness in the general population, the model was highly cost-effective. Considering birth outcomes and infant health in future cost-effectiveness studies certainly would improve cost-effectiveness even further.
Overall, financial incentives produce the largest treatment effects of any smoking-cessation approach with pregnant women, improve birth outcomes and postpartum maternal health, are effective when delivered in community clinics, and are cost-effective. This research illustrates the potential of incentives for promoting meaningful health-related behavior change in a vulnerable population while also guiding extension of this model to other vulnerable populations.
Other Vulnerable Populations
Below, we briefly illustrate research on financial incentives for smoking cessation with adolescents, economically disadvantaged adults, and those with other substance-use disorders or mental illness.
Five controlled studies support financial incentives for reducing smoking among adolescents, at initial stages of proof-of-concept (Corby, Roll, Ledgerwood, & Schuster, 2000; Krishnan-Sarin et al., 2006) and efficacy testing (Gray et al., 2011; Krishnan-Sarin et al., 2013; Reynolds et al., 2015). Examining the efficacy of a high school–based intervention (Krishnan-Sarin et al., 2013), 72 adolescent smokers interested in quitting were randomly assigned to a 4-week intervention where they received cognitive behavioral therapy (CBT) alone, financial incentives alone (US$262 maximal earnings), or combined CBT plus financial incentives. Biochemically confirmed abstinence rates differed significantly between the CBT alone, incentives alone, and CBT plus incentives conditions, with confirmed abstinence rates of 0%, 36.7%, and 36.3%, respectively. At follow-ups, abstinence rates continued to favor the two incentives conditions at one- (4%, 7.1%, and 20%, respectively) and 3-month (0%, 7.1%, and 7.1%, respectively) post-treatment assessments, but were no longer statistically significant. Offering the intervention in the school setting is an innovative strategy to investigate further.
As discussed, adults with less education or low incomes are at greater risk of smoking than those who are more affluent. For example, prevalence among U.S. adults with less than 12 years of education, a high school diploma, or an undergraduate degree is 23%, 22%, and 8%, respectively. Similarly, smoking prevalence among those with annual incomes below versus at or above the federal poverty level is 26% and 15%, respectively. These disparities in smoking prevalence and associated adverse health impacts have tobacco researchers searching for new cessation strategies. Four controlled trials published in peer-reviewed journals support the efficacy of financial incentives for biochemically verified smoking abstinence among economically disadvantaged adult smokers. Treatment effects were assessed only during and immediately following the incentives intervention in two trials (Businelle et al., 2014; Stoops et al., 2009) but as far out as two months (Kendzor et al., 2015) and 1 year (Etter & Schmid, 2016), each of the latter supporting post-treatment efficacy. To illustrate (Etter & Schmid, 2016), 805 smokers were recruited from the general adult population in Geneva, Switzerland. All had annual incomes within the least affluent one third in that geographic area. All participants received a smoking-cessation booklet and access to a cessation website. A subset of 401 participants were randomly assigned to also receive financial incentives contingent on biochemically verified smoking abstinence. Maximal earnings were US$1,650, and incentives increased in value contingent on consecutive negative abstinence tests. Seven-day abstinence rates were significantly greater in the incentives compared with no-incentives conditions at 3- and 6-month assessments (54.9% vs. 11.9%, 44.6% vs. 11.1%), and also at the 18-month assessment (18.2% vs. 11.4%), 1 year after incentives were discontinued.
In contrast to the 17% smoking prevalence seen in the general U.S. adult population, the vast majority of individuals with other substance-use disorders are smokers, with, for example, rates of 75% in alcohol-dependent (e.g., Cooney et al., 2016) and 80% to 90% opioid-dependent clinical populations (Sigmon et al., 2015). Populations with other substance-use disorders also have tremendously high rates of smoking-related adverse health impacts. Eleven controlled studies in peer-reviewed journals have examined financial incentives for reducing smoking in populations with other substance-use disorders, including five among those enrolled in outpatient opioid-substitution therapy (K. M. Dunn et al., 2010; K. E. Dunn, Sigmon, Thomas, Heil, & Higgins, 2008; Schmitz, Rhoades, & Grabowski, 1995; Shoptaw et al., 2002; Sigmon et al., 2015), three receiving other outpatient substance-abuse services (Cooney et al., 2016; Drummond et al., 2014; Wiseman, Williams, & McMillan, 2005), and three among individuals enrolled in residential treatment (Alessi & Petry, 2014; Robles et al., 2005; Rohsenow et al., 2015). The majority of studies are proof-of-concept or early-stage efficacy investigations (Drummond et al., 2014; K. M. Dunn et al., 2010; K. E. Dunn et al., 2008; Robles et al., 2005; Schmitz et al., 1995; Sigmon et al., 2015; Wiseman et al., 2005) with a subset structured as later-stage efficacy trials (Alessi & Petry, 2014; Cooney et al., 2016; Rohsenow et al., 2015; Shoptaw et al., 2002). Five of seven of the more preliminary studies and all of the treatment-outcome trials reported significant reductions in smoking. However, none of the five studies that examined post-treatment cessation demonstrated significant increases in cessation rates.
Prevalence of smoking among those with mental illness is several orders of magnitude greater than in the general population. For example, smoking prevalence among U.S. adults with schizophrenia or affective disorders is 60% to 90% and 45% to 50%, respectively, compared with less than 20% in the general population. Not surprisingly, rates of adverse health impacts of smoking are also high among those with mental illness. Four controlled studies examine incentives among smokers with mental illness, with three being proof-of-concept studies (Roll, Higgins, Steingard, & McGinley, 1998; Tidey, O’Neill, & Higgins, 2002; Tidey, Rohsenow, Kaplan, Swift, & Reid, 2011) and one an early-stage efficacy trial (Hertzberg et al., 2013). All showed reductions in smoking during treatment with incentives, with those reductions being statistically significant in three of the four (Roll et al., 1998; Tidey et al., 2002; Tidey et al., 2011); the Hertzberg et al. (2013) study produced substantially larger cessation rates among those treated with incentives versus controls, although that difference was not statistically significant given a small sample size.
Incentives in Promoting Other Health-Related Behavior Change in Vulnerable Populations
Considering that cigarette smoking kills approximately 480,000 individuals in the United States annually and five million globally, it makes sense that we prioritized it in this review. However, it would be a mistake to conclude that smoking cessation is the only place of substantial promise in using financial incentives to promote healthy behavior change in vulnerable populations. Two new and promising areas of incentives research are preventing unplanned pregnancies among opioid-dependent women (Heil et al., 2016) and increasing adherence to cardiac rehabilitation among Medicaid patients (Gaalema et al., 2016).
Conclusion
The nation needs more effective strategies to promote smoking cessation and other health-related behavior change in economically disadvantaged and other vulnerable populations. Although financial incentives are certainly no silver bullet, a striking amount of empirical evidence indicates that they can be as effective, if not more, than any other smoking-cessation intervention for vulnerable populations available at this time. The evidence supporting their efficacy, effectiveness, and cost-effectiveness with pregnant smokers is solid. We know of no alternative strategy in this population with comparable support. The evidence on the efficacy of financial incentives for smoking cessation in other vulnerable populations is compelling at the level of proof-of-concept and early-stage efficacy testing (i.e., vulnerable populations respond to financial incentives), but the research needs further development in larger efficacy trials powered to assess longer term outcomes, as well as effectiveness and cost-effectiveness studies. The studies on the efficacy of financial incentives in promoting contraceptive use and adherence to cardiac rehabilitation illustrate the breadth and potential of this behavior-change model for addressing critically important but often ignored challenges to improving health and reducing disparities in vulnerable populations. Financial incentives can contribute to promoting health and reducing disparities in vulnerable populations. Cost-effectiveness will likely determine whether we realize their potential.
Footnotes
Authors’ Note
The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Preparation of this article was supported in part by a Centers of Biomedical Research Excellence P20GM103644 award from the National Institute on General Medical Sciences, and Research Awards R01HD075669 and RO1HD078332 from the National Institute of Child Health and Human Development.